XML has become the de-facto standard for interchanging data over the internet in the past decade. However, most enterprise data do not reside in XML format. Rather, they are stored in traditional database systems such as relational database systems and object-relational database systems. Each of these systems stores data efficiently in its own format. Thus, web programming often requires converting data between the format of the data in the database and the XML format. To much relief of web programmers, the database vendors now provide XML features with most database systems.